The rate of de novo CNVs in healthy controls

BackgroundCopy number variation (CNV) is an important cause for human disease. Due to relatively high selection pressure operating against pathogenic CNVs, their rate is maintained in the population by de novo formation. The rates of de novo CNVs are increased in neurodevelopmental disorders. However only a few studies have been performed on relatively healthy individuals, making it problematic to calculate the magnitude of this increased rate. MethodsThe UK Biobank recruited about half a million randomly selected middle-aged members of the general population of the UK. We re-constructed family relationships from the genotypic data and identified 923 parent-offspring trios that passed out quality control filters. Potential de novo CNVs of >100 kb in size were identified and the log R ratios (LRR) and B allele frequency (BAF) traces of the trio members were visually inspected for those regions. We had no opportunity to validate CNVs with a laboratory method, but the traces appeared conclusive. Results and DiscussionWe identified 10 CNVs >100kb in size, a rate of 1.1%. These rates are very similar to those in previous large studies. Using previous large studies, we provide overall rates among 4844 trios for different size ranges that are expected in relatively healthy populations. These rates can be used for comparison in studies on disease populations.